Why Is My Air Conditioner Frozen?

When your air conditioner is iced over, your home can heat up quickly. This is a common, though frustrating, problem, and it’s one you should learn how to troubleshoot. It doesn’t matter what type of air conditioner you have—it can freeze up if conditions are right, and failure to address the problem could lead to costly damage to the unit. Keep reading for some common reasons why your air conditioner may be icing over.

Understanding How the AC Unit Works

Your air conditioner uses a principle of thermodynamics to make your home feel cooler. This principle states that as a gas expands, its pressure and temperature both decrease. Similarly, as it is compressed, the temperature and pressure increase. In the air conditioner, the evaporator coil expands the refrigerant, causing pressure and temperature to drop quickly. This refrigerant comes in contact with the outside air, absorbs the heat, and transports that heat outside where the refrigerant is compressed as the heat is released to the outside air. This cycle repeats over and over to keep your home cool.

So, what does this have to do with an iced over air conditioner? If anything in the way the air conditioner runs is changed, the evaporator coil cannot expand the refrigerant. This, in turn, causes the coil to cool more than it should, and the unit freezes.

What Causes an AC Unit to Freeze Up?

The key to understanding how to fix the air conditioner when it is frozen is learning how to spot the problems that throw the system out of whack. Here are some common reasons.

1. Air Not Flowing Properly Across the Evaporator Coil

In order for the air conditioner to properly take heat from the air inside your home, air must blow over the evaporator coil. If there is no air flowing around the evaporator coil, the refrigerant can’t remove heat from the air inside your home. This means the temperature will just continue dropping, causing the unit to freeze.

2. Low Refrigerant Levels

When the refrigerant in your system leaks, but everything else stays the same, the system will continue to expand the remaining refrigerant. Because there is less, this will create a cooler temperature, eventually dropping below freezing and icing over. Refrigerant leaks or low refrigerant levels are one of the most common reasons for a frozen air conditioner.

3. Running the AC When Outside Temperatures Are Too Low

If you are running your air conditioner and the temperature outside your home is 62 degrees or so, the system cannot run as it was designed to. The pressures will drop too low and the system will freeze. In this instance, simply turn off the system, open your windows, and enjoy the fresh air!

4. Mechanical Failure of the System

Problems with the refrigerant lines, broken blower fans, clogged air filters—all of these types of mechanical problems can cause the air conditioner to freeze up. Fixing the problem will thaw the unit.

What to Do if Your AC Freezes

So, what can you do if your air conditioner is frozen? If the problem is not a dirty air filter or running the system when it’s too cool out, you need to call a qualified air conditioning professional. This is not a problem to ignore, because continuing to use the unit will cause more serious and costly problems.

For homeowners in Northern Kentucky, Arronco Comfort Air is ready to serve. Contact us today to discuss your frozen air conditioner with one of our HVAC experts, and let us help you find the problem so you can start enjoying a properly cooled home again.